Our night started with "Yappy Hour"; our trainers monthly get together at a local coffee bar. While there, Nisha one first place at the trick contest

! She was fine the entire time there, and was leashed to me the entire time.
After leaving "yappy hour" we went to Home Depot to purchase some air filters. We are remodeling, so this is a weekly (if not bi-weekly) occurance for Nisha. We walked towards the door, and into the room where you get carts. There was a "cart man" pushing a row of carts behind us; I noticed Nisha watching him, but no unusual behaviors yet. I went to grab our cart and noticed Nisha starting to crouch and get nervous (the cart man was coming up behind us)...all of a sudden BAM; total and complete freak out. Screaming, whining, foaming, and trying to run and escape everything. I swear, it sounded as if I was stabbing her repeatedly. She was so loud, and completely freaked. I calmly walked out of the store to a bench outside. We stayed there for a minute or so, but she was still "verbalizing" her scared state of mind. We went back to the car and went home. For about 5 minutes in the car she was panting, pacing, and foaming at the mouth. Finally, she calmed down. I was at a complete loss, and figured it was because the cart man scared her. Nisha is very socialized to many different situations; she has NEVER been more scared than a simple "twitch". I swear to you, she has NEVER acted even remotely like this.
So, everything is fine...I have plans to take her to Petsmart tomorrow to re-aquaint her with carts. Jesse (boyfriend) goes in the backyard with Nisha (its dark...around 10:00) to take her potty; while out there he picks up the drop cloths (from painting) and tosses them so they hang over the fence to dry. Nisha FREAKS again

. Loud, howling, trying to escape, foaming...complete and utter freak out. Almost like she is on drugs or something. She runs inside and climbs on the window like she wants to jump out. I (fearing she might try) get her off the ledge and guide her to her kennel. She races in and crouches in the back...still crying and whining. I tell Jesse to just leave her alone; he talks to her a few times, and she just starts whining more. After maybe 45 seconds we leave the room to let her get over it. (I didn't want to re-inforce the behavior).
I have no idea what is wrong; Nisha is so acclimated to things. We socialize her all the time. At least twice a week she goes into a "store" with carts. She has never shown any fear towards anything; in house or out.
She is 15 months, and spayed.
Some ideas we (actually Jesse) had....
1) we saw a giant frog in the backyard; could she have eaten it and been poisoned? She is never "locked" out; I think I would have noticed her eating a frog...but who knows. No vomiting though.
2) I had some old treats I was using...Natural Balance "log" type food. We cut it up into small treats for training. I think they could be a month old or so. Could they be bad?
I think something is going on mentally; I mean she is totally acting psycho. She IS NOT a scared/soft dog....until now.
I will call the trainer tomorrow; but what do you think. HELP!!! We are so worried. Could she just be "going crazy" for no reason, and out of the blue?
~being completely honest when I say....she has never shown any "fear" or nervous signs to anything. To see her completely freak is scary to me and Jesse. I am so nervous that all our socialization and training has gone down the drain; I fear that I will be working for months on end trying to re-socialize her

.
Could she be sick? Jesse thought maybe her vision is off (things are scaring her b/c she cant see clearly); but I don't think so.